1. Field of the Invention
The present invention relates to a speech recognition method and to a speech recognition apparatus capable of simultaneously performing the detection of a section of input speech containing a word and recognizing a word based on a comparison with a reference pattern of the word.
2. Description of the Related Art
One known speech recognition method is the word spotting method which can simultaneously detect a section of input speech containing a word and recognize a word contained in input speech information.
The word spotting method calculates the difference between a reference pattern of a word and a parameter obtained from input speech to be recognized, while shifting the reference pattern by one frame with respect to a power time series of the input speech parameter. This difference is called the distance between the reference pattern and the section of the input speech containing a word. The word spotting method recognizes that a word corresponding to the reference pattern exists in a portion of the input speech when the distance falls below a predetermined threshold value.
However, such a conventional word spotting method cannot correctly perform recognition in the case in which a certain word includes another word as a part thereof, for example, "roku" (six) includes "ku" (nine) or "sici" (seven) includes "ici" (one).
In one example of "roku" and "ku" shown in FIG. 6, a reference pattern for "ku" is matched with two input sounds: the word "ku" and the syllable "ku" which is a part of the input word "roku", thereby resulting in incorrect detection.